Moving stairway brake



Jan. 25, 1949. G. w. LAUTRUP ET AL 2,460,017

MOVING STAIRWAY BRAKE 3 Sheets-Sheet 1 Filed June 6, 1946 a a INVENTORS BY ATTORNEY Jan. 25, 1949. G. w. LAUTR UP ET AL 7 MOVING STAIRWAY BRAKE Filed June 6, 1946 3 Sheets-Sheet 2 FIGZ 8 g Q WM INVENTORS ATTORNEY Jan. 25, 1949. G. w. LAUTRUP ET AL. 2,460,017

' MOVING STAIRWAY BRAKE 3 Sheets-Sheet Filed June 6, 1946 44 a; 45 45 v T 92, e 9s 54 47 I5 'i" 4 46 D--' 46 2 40 U FIG. 7

I NVENTORS which,' with the force due to the stopping Patented Jan. 25, 1949 ,450 017 MOVING SIA AY BR K George Wi li m au ra n e s d h Norman Anderson, ltloboken, N. 5., assignors to Otis Elevator Company, New liork, N Y., a coraerati ew J ts Application June 6,

4 Claims. (01. lea-c9) The invention relates to moving stairway brakes and to the control thereof.

Moving stairways are provided with brakes which act, when the u p Qt o e o t e d i motor i iscon inued brin t tai way to a stop. The discontinuance of the power supply to the driving motor is usnally not only effected by manual control but also by the operation of various safety devices. Also power failure may occ rth wer pp may be discontinued under conditions where persons are using the stairway. It is desirable when this occurs that the stairway be brought to a stop without throwing passengers off balance.

It is the object of the invention. to provide braking apparatus which, upon the discontinuance of the power supply, acts to apply an initial braking force and after a certain time interval to ap y d i al bra n force e rc f which combined with the initial braking force is sufiicient to stop the stairway regardless of the load thereon.

In the arrangement which will be described, the brake is of the pawl operated type. A pair of brake rings with ratchet teeth is provided and an operating pawl is provided for each brake ring. During running of the stairway, the pawls are held in retracted positions disengaging the brake rings and these rings and other parts of the brake apparatus rotate as a unit through a clutch action. Upon the discontinuance of the power supply to the driving motorfo'rany" reason, the pawls are freed for engaging the respective brake rings, one pawl being freed first and the second upon the eirpirati'onof a certain time in s' he a e If h sta wa sdes e ine at the time, the first pawl engages a tooth on thebrake ring for which it is provided to bring the ring to a stop. As a result a certain brakin force is erge'rt d'which is suflicient to effect a gradual Step c he s ai way w hin h tim interval, if lightly loaded. 1f the stairway is still descending when the second pawl is freed, this pawl engages a tooth on the brake ring for eh' i ded. t b in th r n to a top- As a result, additional braking force is provided o he first ring, is sufficient to bring the stairway to a gradual stop, even if heavily loaded. In this way, the possibility of throwing'passengers off balance is nn indeed. It the stairway is ascending at the timathe pawls do not engage the teeth'to'bring the stai f ay t a stop but the time interval is of slichdiirationthatjboth pawls will e in a t en was. ,hfl e h q: the this? 1946, Serial No. 674,738

and thus prevent appreciable downward movement of the stairway; should the load on the stairway be such as to cause reversal to take place. In the preferred arrangement, each pawl s Provided wi a d-of shoe o pr e t e pawl, when freed under conditions Where the stairway is ascending, engaging the ring teeth until after the stairway has ceased its upward movement.

Features and advantages of the invention will be seen from the above statements and from the following description and appended claims.

In the drawings:

Figure 1 is a diagrammatic representation in side elevation oi" a moving stairway embodying the invention; I

Figure 2 is an end view, with parts in section, of the stairway brake of Figure 1;

Figure 3 is a side view of the same, in section taken along the line 3 3 of Figure 2;

Figure 4 is a view in section taken along the line 4-4 of Figure 3;

Eigure 5 is an enlarged detail, with parts broken away of a portion of the brake mechanism as viewed ironi the top;

Figure 6 is a side View of the same, with parts omitted; and

Figure 7. is an across-the-1ine wiring diagram of a portion of the control circuits for the stairway directed to the control of the brake.

Referring to Figure 1, the moving stairway extends between a lower landing it and an upper landing Ii. It comprises an endless series of steps i2 driven at the upper end or the stairway by means of sprocket wheels through running gear chains, aisprocket wheel and chain being arranged on each side of the stairway.' A sprocket wheel and running gear chain are i1- lustrated diagrammatically for one'side ofthe stairway, the sprocket wheel being designated l3 and the chain I4. The sprocket wheels are mounted on and driven by the main drive shaft I5 of the stairway. This drive shaft, in turn, is driven by an electric motor 55, through reduction gearing IT, sprocket wheel 48, driving chain 19 and sprocket wheel 29 secured to shaft i5, chain i9 and wheels l8 and '26 also being diagrammatically illustrated. v

The stairway has two endless moving handrails, one at each side thereof, operating at substantially the same speed as the steps. The handrail 2| for one side of the stairway is shown and is diagrammatically illustrated as driven from main drive shaft 15.

The stairway is provided with a break which acts on the main drive shaft i5 and is designated as a whole as 39. Details of the brake are illustrated in Figures 2 to 6 inclusive to which reference maynow be had.

As illustrated in Figure 2, the brake is associated with the sprocket wheel l3 on one side of the stairway, being interposed between the sprocket wheel and the stairway trust 31. The

. brake'comprises a mounting ring 32 secured to sprocket wheel 53 as by bolts 33. Ring 32 is formed with a flange 34 and a barrel portion 35 which extends from the flange toward the truss. This barrell portion forms a support for the pressure ring 35 and an intermediate ring or annulus 31. The pressure ring and annulus are driven from the mounting ring through a key 38, being slidable on the mounting ring. The pressure ring is formed with a cylindrical per;- tion 49 which fits onto the barrel portion 35 and a flange 4i coextensive with flange 3d. Annulus 37 is formed 1 with a like cylindrical portion 42 and flange 43. Arranged on cylindrical portion 49 between flanges 4| and 33 is a brake ring 46. Alike brake ring 35 is arranged on cylindrical portion 42 between flanges wand 34. Each brake'ring is provided with an inner bushing 46 which fits on the cylindrical portion on which the brake-ring is mounted to form a bearing for rotative movement of the cylindrical portion with respect to the brake ring when the brake ring is heldagainst movement. Each brake ring is also'provided on each side thereof with a friction lining 4?, preferably in the form of a plurality of segments embedded in pockets 38 formed in the'sides of the brake ring. These segments act when the brake ring is free to rotate to provide a frictional driving relationship between the ring and the adjacent flanges and when the ring is stopped to exert a braking force against the flanges. A plurality of springs 58 are arranged in pockets 5i formed inside the barrel of the mounting ring. 'Each oi these springsis arranged on a bolt 52, the threaded end of which extends through aperture 53 in the base 5 5 of the pocketand aperture 55in the pressure ring 35 where it is provided with a nutSE. The springs are compressed'between the bases 5-! and spring seats 5? formed on head ends of the bolts and act to push the pressure plate toward the mounting ring, clamping the brake rings between the flanges to be driven by the sprocket wheel through a clutch action and to cause a braking'force tobe exerted on the flanges through the friction linings when a brake ring is stationary and the rings on which the flanges are formedare turning. -The amount of braking force is adjusted by adjusting nuts 56.

Each brake ring is provided with a plurality of ratchet teeth 6% extending in a direction for engagement by a pawl to prevent rotation of the ring in the direction for downward movement of the stairway.- These pawls are preferably positioned on opposite sides of the main drive shaft as illustrated. The pawl 61 for brake ring 34 is pivotally mounted on a bracket 62 secured to the truss framework while the pawl 63 for brake ring 35 is pivotally mounted on a bracket 6d, also secured to the truss framework; Each of these pawls is formed on 9. mb 55 through which the pivot pin 55 for the pawl extends. An operating arm for the paWlis also formed on the hub, the operating arm for pawl 95 being designated 67 and that for pawl being designated 68. Arm link it "to a Weighted E? is connected-bye bell crank H pivotally supported by a bracket 12 mounted on an upper memberof the truss framework. The bell crank in turn is connected by an adjustable link 13 to a lever M. This lever in turn is connected to the movable core 11 of an electromagnet 35. This electromagnet is supported in a frame '56 mounted on the-truss framework. The other end of the lever is pivotally supported on the frame it, the core 17 being connected to a mid point on the lever. Similarly, arm 63 is connected" by a link 86 to a weighted bell crank 82 pivotally supported by a bracket 19 mounted on the same member; of the truss but spaced from bracket 125- Bell crank 8! is connected by link '82 to lever 83 which in turn is connected at a midpoint to the'movable core 86 of an electro magnet 84. The electromagnet is supported by a frame mounted on the truss framework beside 'frame 75. The lever 83 is pivotally supported on frame 85, levers 74 and 83 extending in diiierent' directions. With this construction; each electromagnet'wheri energized'acts through its core to pull'the'pawl connected thereto into retracted'positiondisengaging the brake ring and to hold the pawl in that position.

Each of levers 14 and 83 is arranged to operate switching mechanism; this mechanism being located in a hou'singS'I having an opening through which an abutment operating screw 38 mounted on the lever may pass. The cover for the housing for theswitchingmechanis-m operated by lever'83 has been shown removed in order to show the switching mechanism. A switch arm 89 is pivotally mounted "in the housing and has an operating roller to be e'ngaged by the abutment screw. *The switcharm is biased. by a spring against movement by'the abutment screw. The switch is indicated as of the make and break type-the making contacts being designated Q13 and the breakingcontaCtsbeing designated 91. The switching 'mechanism for operation by lever 14 is not shown but may be-of the same arrangement; although in the preferred control' circuitsa single make type is utilized. Electromagnet15 mayhave a-single magnet coil 92 1 while electromagnet 84- has -preferably two coil portions; eitherin the form of separate coils '93 and 94- asindicated or'in the form of one coil with a connecting tap. a a

As illustrated in Figures-dand 6,--pawl 6| carries a pivotedshoe 95in position opposite the rim 96 of flange 4!. Similarly pawl 63- carries a pivoted shoe ST-inpositionopposite the rim 98 of flange 34.- Each shoejis formed of two arms, one arm for engaging a' pin lflfl" carried by the pawl. The shoe is biased by weight distribution in a direction so that the other; arm'lfll ,of the shoe extends toward the'rim. When the stairwayis ascending the brake rings are'rotating in the direction of the arrow marked up in Figure 6,=and when the stairway is descending the-brake rings are rotating in the direction of thearrow marked down. Whenan electromagnet'releases its core, the pawl connected't-hereto is moved by. the weighted bell crank in a direction; for engaging ratchet teeth." *In' the initial movement of:the pawl; the'arm' I0 I of its-shoe engages the rim. Should the moving stairway *be descending at the time electromagnet45 "releasesj its". core, the arm toward brake ringfd d. The irictionalforcethereshoe into position tosperm tcontinuedmovement of the pawl into-1 positionft'o" en age. ajratchet tooth; '--Similarly,- if the stairway is still descendage -ow ing at the time electro ma'gnet 8 4 releases its core, shoe 91"is similarly infidpos'itien to enable pawl 53 to more into posiionroeri'ga e a i'at'bhet tooth. When the stairwa is ascendi'rigthe shoe for each pawl, when 'the'fpawl is nee by its elec? tromagnet; engages the rim and is held 'in'p'o'sitioh against the pinWHU by the"rrictionarrorce exierted thereon by th The arm IBI is'of'such length as to prevent the pawreh agm the ratchet teeth so iqhg as the oe maintained in this position This obviates the paWl's ounc ing over the teeth, with attendant noisean onnecessary wear or the various"operating arts. Should. the stairwaystart remove downwardly after ascending movement stops; the "sho s" are swung inthe other direction about their pivots; permitting the pawls to n'ga'gethe ratchet teeth.

Reference may now behad to Figure "7 which illustrates controlling circuits for th'eboil's 92', 93 and 94 er the'electroni'agn'ets The censor these electromagnets are subject to a switch 'H which is operated to engage its contacts'incident tothe starting of the stairway in either direction. This switch is further controlled so a todrop out to separate its Contacts upo'nthe discontinuance of the power supply to the stairway-driving motor. Contacts 185 are separated when the coil 92 of electromagnet I5 is energized to retract 'pawlBL these contacts being either contacts of the switching mechanis m'in housing 81 or contacts of a relay controlled by this switching in'echa nism. The outercoil 93'alone of electromagnet 8A; is strong enough when energized to'retract pawl 63 Contacts 91 of the switching mechanism operated by 'electromagnet '84 "separate "as" the pawl is retracted to remove'a short circuit for the inner coil 94. The outer coil is of relatively heavy wire while the inner coil is'of relatively fine wire or a larger number of turns." he insertion of the inner coil in series with the outercoil'reduces the ampere turns or the electromagnet'to a pointstill sufficient to hold the pawl released, but without dissipating energy. When the circuit forcoil 93 is completed, a circuit is also completed for charging a condenser {01, this circuit being through resistance tilt to limit the initial char'ging current. "When the external supply ofcurrent to coils 93 and 9*} is discontinued from any cause, including failure or power, the condenser discharges into these coils'to supply sufficient current thereto to hold core 8;; in attracted position and thus maintain'pawffi3retracted for a certain time interval. Ihe relatively large number of turns added by coil 94"t'o those of coil 93 enables a time interval of the desired duration to be obtained'with a condenser which is not pro-. hibitively large. I

'In operation, when the moving stairway is idle, the pawls El and 93 are in engagem'entwith ratchet teeth as illustrated for example in Figure 3. Upon operation of switch I-I incident to the starting of the moving stairway, contacts HI and H2 engage, completing the circuits for the coils 92 and 93 respectively. As a result, the electromagnets l5 and 84 act to attract their cores 1'! and 86. This movement is transmitted through the lovers and linkage connecting the pawls BI and 53 to cores Ti and 86 respectively to move the pawls about their pivots into positions to clear the ratchet teeth. Should the stairway be started ioroperation in the down direction, a short initial movement of the stairway in the up direction is effected to enable the pawls, if wedged against teeth, to be disengaged from the ratchet teeth before circuits are established for downward move- 6 met, similar to the usual manner of controlling si r'igle'pawlbralies." Whenthepawls are retrac't" their respect-r switching "mec anisms are" op' erated' resulting-in the" separation or 'cfii'ltacts i 05 te'ifiseitrsistanoe iiliiin series Withoil gland in the separations; co 'tacts "9i to'inse'rt coil94 in series with any 93CfAl'so' the engagement of contacts H2 completes the "charging'circuit for cbpiahserllm. c "Withth pawls retracted, the brake rings are rotated with the sprocket, mountin'g' ring and ressure ring through a clutch action; Should a stop button be operated to stop the 'stairwiyfidr should saiety" device operate, switch H is dropped out't'o separate contacts Hi and H2. This disconnects coils 92, 93 and 94 from the sup"- m lines;

The core of electromagnetfiii is 'r= leased immediately but condenseriiil'l discharges into cells 93 and 94' to maintain suificient energization thereof to prevent the immediate rel'eas'ecf thecor'e of electromagnet 84.' This is true also in case of power failure.

Assume that the moving stairway has been descending. The release of the core of the electromagne't i5 permits the weighted bell crank it to act through link 18 and operating arm 61' to rotate pawl El about its pivot into position to engage one of the ratchet teeth 60 on the 'rim of brake ring M, the shoe 95 being swung out of the way immediately that it engages the rim'96'. Upon the engagement of the pawl'with a ratchet tooth, rotary 'movernent of the brake ring is immediately'stopped with the result that a braking' force is exerted through the friction linings i'l' on the flangesei and d3 for stopping the stairway. Upon the expiration of a certain time interval, the "condenser *lo'l'discharges toa'point' where the electromagnet 84 is no longer capable of 'inain'taining' its core in attracted position; As a result, the core is released and the weighted bell crank 8i acts through link 86 and operating ever, should arm 68 to move pawl 63 about its pivot in 'a threetion toward the brake ring 45.' If the stairway has been brought to a stop by the braking force exerted as a result of the stopping of brake ring M, the movement of the pawl is stopped upon the engagement of shoe 91 with rim 98. 'l'low the stairway still be descending at the time this movement of pawl 53 takes place; shoe 9! is immediately" swung'out of the way as it engages rim es, permitting'the pawl'to engage one of the teeth 60 o'n'brake ring 45. Asthis engagement takes place, the ring is brought to an immediate stop and an additional "braking force is exerted through 'the friction linings upon flanges 34 "and 43 to'br'ing the stairway the stop; '"The combined braking forcesdue to the stopping of bothbrake'rings'is sufficientto bring thestairway to a stop regardless ofloa'd. *smma the stairway hav'b'ee'n" ascending at the time of the discontinuence of the supply of current from the supply lines to the coils of the electromagnets, no braking action is exerted by the braking mechanism and the stairway coasts to a stop. Pawl 6! does not move into engagement with its brake ring on the release of core H, being held off by the action of shoe 95. similarly, shoe s'l holds pawl 63 oii its brake ring on release of core 86 by electromagnet 84 upon the expiration of the time interval, this time interval expiring before the stairway coasts to a stop even though heavily loaded. Thus, when the stairway comes to a stop, both pawls are in condition to move into engagement with teeth on their brake rings should the stairway because 0:

7 the; {load thereon start rto move' downwardly. Should-: this downward ;movement;.;;occur, athe pawls engageteeth on the brake rings :during the initial downward movementgto preventany-appreciable downward movement-of the-;;stairway;

\Thus it seen that braking apparatus is pro;-' vided for a moving stairway in which an;; initial braking'force is applied to stop: a descending stairway and, if the stairway is not :brought ;to astop within a certain time interval; .an-aidditional braking force is applied. The amount :fot the initial braking force is such. as toieffeot 517.116 stopping of the stairway, if the load thereon does not. exceed a certain amount, at:,a:;retardation rate :which minimizes the possibility ofxpas: sengers being thrown off balance. The amount of the total'braking force when the additional braking force islappliedxissuchv as to efiectithe stopping of the stairway if heavily loadedrat-za comparable retardation rate. Thisarrangement insures the stairway being brought to a stopibut without the application of a brakingforcerwhich might cause an abrupt stop. I a -Itwill also be seen that a simple and economical arrangement is'provided for applying the braking force in steps. Various changeszin the construction andcontrol of the brake may be made. For example, the brake may be arranged to be applied ina greater number of gstepsx Also, different timing arrangements may be employed butthe one illustrated has the advantage of pro: vidingtiming in case of p-owerrfailurer vAs'inany changes could be made in the above construction and many apparently; widely different embodiments of this invention "could be made .without departing from thezscope thereof, it is "intended that all matter: containedrin the abovesdescription .or shown in the accompanying drawings shall be interpreted as illustrative and not inla limiting sense. T 1 a 1 :What is claimed is: I

11'. Braking apparatus comprising;- a plurality of rotatable members; a plurality of brake mem: bers alternately positioned between said rotatable members and in frictional engagement therewith to be rotated thereby; stopping means for each of said brake members for engaging the same to stop rotation thereof; an electromagnet for each stopping means for disengaging it from the brake member for which-it is provided; and means for causing said stopping means to engage said brake members in timed sequence. 7

'2. Braking apparatus comprising; a plurality of rotatable coaxial rings; a plurality of brake rings, one less than the number of coaxial rings, alternately'mounted between said coaxial; rings, each brake ring having a plurality of circumferential teeth thereon; means for'yieldably clamping said brake rings between said coaxial rings for rotation therewith; a pawl for each of 'said -SMBraKing apparatus comprising; three spaced coaxial-rings rotatable as a unit; two brake rings alternately-mounted between said coaxial rings, each: brake ring having a plurality of ratchet teeth: onflthe periphery .thereof extending in the direction. of-rotativemovement of said coaxial rings'iin -a;certain direction; friction facings for thev sides of saidbrake rings for engagingsaid coaxiale-rings; 'means vfor yieldably clamping said brakerings between said coaxial rings; a pawl for-each o;f; s aid brake rings for engaging a tooth vthereon;-;-.;.-anelectromagnet for each pawl for movingithe pawl to and holding it in retracted position; i disengaged from the ratchet teeth of the brake ring for which it is provided; means for each; pawl for biasing it to tooth engagingposition;;means for each pawl for preventing its moving into tooth engaging position exceptgwhenthere is, rotative movement of said coaxialrings in said certain direction; and means for causing said pawls to move into tooth engaging position in timed sequence, whereby when said coaxial rings are rotating in said certain direction thebraking action is exerted in steps. 7 V Braking "apparatus comprising; rotatable mean sga brake ring frictionally driven by said rotatablemeanssaid brake ring having a plurality of ratchet teethextending in one direction of rotative movement of said rotatable means; a pawl biasecl'to engage said teeth; an electromagnet; adapted upon energization to, retract said pawl fromsaid teeth; and means rendered effectiveuupon deenergization of .said electromagnet for holdingthe pawl oif the teeth except when there is movement of said rotatable means in said one direction. Y a

l. GEORGE- WILLIAM 'LAUTRUP.

'JOHN NORMAN ANDERSON.

, V REFERENCES CITED The following references are of record in the file of this patent:

were STATES PATENTS Number Name D-ate 767,742 Ferguson Aug. 16, 1.964

960,055 I Sundh May 31, 1910 

